Priming material for substrate coating

ABSTRACT

A coating technique and a priming material are provided. In an exemplary embodiment, the coating technique includes receiving a substrate and identifying a material of the substrate upon which a layer is to be formed. A priming material is dispensed on the material of the substrate, and a film-forming material is applied to the priming material. The priming material includes a molecule containing a first group based on an attribute of the substrate material and a second group based on an attribute of the film-forming material. Suitable attributes of the substrate material and the film-forming material include water affinity and degree of polarity and the first and second groups may be selected to have a water affinity or degree of polarity that corresponds to that of the substrate material and the film-forming material, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/133,755, filed Mar. 16, 2015, titled “Priming Material for SpinCoating”, the entire disclosure of which is incorporated herein byreference.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experienced rapidgrowth. In the course of IC evolution, functional density (i.e., thenumber of interconnected devices per chip area) has generally increasedwhile geometry size (i.e., the smallest component (or line) that can becreated using a fabrication process) has decreased. This scaling downprocess generally provides benefits by increasing production efficiencyand lowering associated costs. However, such scaling down has also beenaccompanied by increased complexity in design and manufacturing ofdevices incorporating these ICs, and, for these advances to be realized,similar developments in device fabrication are needed.

As merely one example, many fabrication steps involve the formation andmanipulation of thin films of material formed on a substrate or wafer.Defects, imperfections, irregularities, and contaminants in these filmlayers may undermine the fabrication process and may precipitouslyaffect both yield and device performance. As films are layered upon eachother, the effects of even small imperfections in underlying layers maybecome magnified. Thus, the importance of uniformity and preciseapplication cannot be overemphasized.

Spin coating is one technique for forming a thin layer of material on asubstrate that has proved satisfactory in some applications. Spincoating may involve depositing a material in liquid form at the centerof a substrate and spinning the substrate to drive the liquid to theedges. In this way, spin coating leverages the centrifugal tendencies ofthe liquid to produce a film of significantly uniform thickness.

However, while existing spin coating techniques have been generallyadequate, the potential for future improvements still exists. Forexample, uniformity of the final film may still be improved. As anotherexample, because many advanced fabrication processes rely onincreasingly expensive materials, improved coverage using less liquidmay meaningfully reduce cost per device. For these reasons and others,additional improvements to spin coating techniques hold the potential toimprove fabrication yield and to reduce cost and waste.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is a side view of a spin coating system according to variousaspects of the present disclosure.

FIG. 2 is a top view of the spin coating system according to variousaspects of the present disclosure.

FIG. 3 is a flow diagram of a method for applying a film to a substrateaccording to various aspects of the present disclosure.

FIG. 4 is a side view of a spin coating system performing the method toapply a film to the substrate according to various aspects of thepresent disclosure.

FIGS. 5-7 are molecular diagrams of chemical compounds suitable for useas a priming material in the method of applying a film according tovarious aspects of the present disclosure.

FIGS. 8-11 are further side views of the spin coating system performingthe method to apply a film to the substrate according to various aspectsof the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to IC device manufacturing and,more particularly, to an improved technique for spin coating thatutilizes improved priming materials.

The following disclosure provides many different embodiments, orexamples, for implementing different features of the disclosure.Specific examples of components and arrangements are described below tosimplify the present disclosure. These are, of course, merely examplesand are not intended to be limiting. For example, the formation of afirst feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,elements described as being “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the exemplary term “below” can encompass both an orientation ofabove and below. The apparatus may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein may likewise be interpreted accordingly.

The present disclosure relates to the application of a material to awork piece, such as a semiconductor substrate, using spin coating orsimilar techniques. An example of a spin coating system 100 suitable forperforming this technique is described with reference to FIGS. 1 and 2.In that regard, FIG. 1 is a side view of a spin coating system 100according to various aspects of the present disclosure, and FIG. 2 is atop view of the spin coating system 100 according to various aspects ofthe present disclosure. For clarity and ease of explanation, someelements of the figures have been simplified.

The spin coating system 100 utilizes the rotation of a substrate 102 todistribute a liquid across the surface. Accordingly, the system 100 mayinclude a rotating chuck 104 operable to retain and rotate the substrate102. The chuck 104 may use any method to retain the substrate 102, andin some exemplary embodiments, the chuck 104 is a vacuum chuck 104.Accordingly, in the illustrated embodiment, a central cavity within thechuck 104 is connected to a vacuum pump. The chuck 104 is sealed againsta back surface of the substrate 102, and air within the cavity isevacuated to hold the substrate 102 in place.

Once the substrate 102 is secured, the chuck 104 rotates around acentral axis 106 causing the retained substrate 102 to rotate as well.Rotational speeds may reach or exceed 3,000 rpm based on theapplication. Because of increased turbulence and rotational instability,maximum rotational speeds for larger wafers tend to be slower, and atypical maximum rotational speed for a 300 mm substrate 102 may bebetween about 800 rpm and about 4,000 rpm. The rotational speed of thechuck 104 (and by extension the substrate 102) may vary throughout thespin coating technique in order to control the dispersal of the liquidbeing applied.

To supply the liquid, spin coating system 100 may include one or morenozzles 108 and associated supply lines mounted on a movable armature110. The movable armature 110 may relocate the nozzles to a “home”position out of the loading path when a new substrate 102 is beingsecured and moves the nozzles into position over a central portion ofthe substrate 102 once the substrate 102 has been loaded. In someembodiments, the moveable armature 110 also allows the nozzles 108 to bepositioned anywhere along the radius of the substrate 102 during thespin coating process. In addition to liquid supply nozzles 108, thesystem 100 may include one or more gas delivery nozzles 108 on thearmature 110 and aimed to direct air towards the substrate surface beingcoated. The gas delivery nozzles 108 may blow ambient air or one or moregasses such as nitrogen, argon, and/or helium on the substrate surface.While the gas is being supplied, the movable armature 110 may sweep thenozzles 108 across the surface of a spinning substrate 102 in order todrive the liquid outward. The air provided by the gas delivery nozzles108 may be heated in order to control viscosity, thickness, evaporation,and/or solidification of the liquids provided on the substrate 102. Forexample, in some embodiments, air supplied by the gas delivery nozzles108 is maintained at about 23° C. in order to keep the liquid viscouswithout over drying.

In addition to a gas delivery nozzle 108 or as an alternative thereto,the spin coating system 100 may include a downdraft air flow device 112that directs air towards the surface of the substrate 102 upon which thefilm is being formed. Similar to the gas delivery nozzles 108, the airflow device 112 may blow ambient air or one or more gasses such asnitrogen, argon, and/or helium at the substrate surface. The airprovided by the air flow device 112 may be heated in order to controlviscosity, thickness, evaporation, and/or solidification of the liquidsprovided on the substrate. In that regard, some degree of evaporationduring the application process may be desirable in order to producethicker films, while over drying may prevent the liquid from fullycovering the substrate 102 before solidifying.

To further control evaporation, the spin coating system 100 may includeone or more heating elements 114 controlled to maintain the substrate102 and any liquids disposed thereupon at a designated temperature. Insome examples, the heating elements 114 are controlled according to acomplex thermal profile that varies the substrate 102 temperaturethroughout the spin coating process. As with the gas delivery nozzle 108and air flow device 112, the heating elements 114 may be used to controlambient temperature and thereby control viscosity, thickness,evaporation, and/or solidification of the liquids provided on thesubstrate 102.

As the substrate 102 rotates, some liquid deposited on the substrate maybe ejected from the substrate 102. Much of the ejected liquid will comefrom the circumferential edge of the substrate 102, although some liquidwill be ejected elsewhere along the surface of the substrate 102. Tocatch this liquid, the spin coating system 100 may include a coater cup116 or dish surrounding the chuck 104 and the retained substrate 102.The cup 116 is shaped to catch the liquid and to prevent the ejectedliquid from dripping or otherwise re-depositing on the substrate 102.Back-splattered liquids that re-deposit on a substrate 102 have beendetermined to cause spotting and other imperfections that may adverselyimpact yield. Depending on the degree of contamination, some of thecaptured liquid may be recycled and reused, although the liquid may alsobe captured for disposal. Disposal is an important consideration becausemany of the liquids used in spin coating have significant disposalcosts. In one example, disposal costs were determined to beapproximately 30% of the material costs associated with applying aparticular photoresist film. In many applications, reducing the amountof liquid used to coat the substrate 102 also reduces the amount ofexcess material to be disposed of.

A technique for utilizing the spin coating system 100 that offersimproved coverage with a reduced volume of liquid is described withreference to FIGS. 3-11. The technique is suitable for use in formingany of a wide variety of films upon a substrate 102, with exemplaryfilms including photoresist films, multi-layer photoresist (e.g.,trilayer resist) films, antireflective coating films (e.g., a bottomantireflective coating (BARC) film), hard mask films, and/or othersuitable films. As explained in more detail below, a priming material isfirst applied to the substrate to facilitate the subsequent applicationof a film-forming liquid by improving the flow and coverage of thefilm-forming liquid. In order to further improve the coverage of boththe priming material and the film-forming liquid, the priming materialmay be tuned based on the film-forming liquid and the layer of thesubstrate 102 being covered. FIG. 3 is a flow diagram of a method 300for applying a film to a substrate 102 according to various aspects ofthe present disclosure. It is understood that additional steps can beprovided before, during, and after the method 300 and that some of thesteps described can be replaced or eliminated for other embodiments ofthe method 300. FIGS. 4 and 8-11 are side views of a spin coating system100 performing the method 300 to apply a film to the substrate 102according to various aspects of the present disclosure. The spin coatingsystem 100 may be substantially similar to that of FIG. 1 and mayinclude a substrate 102, chuck 104, nozzles 108, an air flow device 112,a heating element 114 and/or other elements substantially as describedabove. FIGS. 5-7 are molecular diagrams of chemical compounds suitablefor use as a priming material in the method of applying a film accordingto various aspects of the present disclosure. For clarity and ease ofexplanation, some elements of the figures have been simplified and someelements of the figures have been exaggerated.

Referring to block 302 of FIG. 3 and to FIG. 4, a substrate 102 isreceived and secured within a chuck 104 of the spin coating system 100.The substrate 102 is exemplary of any material upon which upon whichother materials may be formed and may represent a semiconductorsubstrate for circuit fabrication, a mask substrate, and/or any othersuitable substrate for any other suitable application. In variousexamples, the substrate 102 comprises an elementary (single element)semiconductor, such as germanium in a crystalline structure; a compoundsemiconductor, such as silicon germanium, silicon carbide, galliumarsenic, gallium phosphide, indium phosphide, indium arsenide, and/orindium antimonide; a non-semiconductor material, such as soda-limeglass, fused silica, fused quartz, and/or calcium fluoride (CaF₂);and/or combinations thereof. The substrate 102 may also include variousmaterial layers formed upon it. For example, exemplary layer 402 of thesubstrate 102 may represent a semiconductor layer, a dielectric layer, aconductive layer, a polymer layer, and/or other material layers.

In some such embodiments, layer 402 represents a layer of a trilayerresist. An exemplary trilayer resist includes an under layer designed toprovide protection for underlying materials. The under layer mayfunction as a mask to protect the underlying materials (e.g., substrate102) from etching, ion implantation, or other processing. In someembodiments, the under layer includes an organic polymer. The underlaymaterial may be free of silicon in order to provide etchant selectivitywith respect to a middle layer of the resist. In that regard, thetrilayer resist may include a middle layer that includes the organicpolymer with the addition of silicon and/or another silicon-containingmaterial such that the middle layer is sensitive to a different set ofetchants than the under layer. The middle layer may function as an etchmask to transfer a pattern to the under layer. In some embodiments, themiddle layer may further function as a bottom anti-reflective coatingthat reduces reflection during a lithography exposure process, therebyincreasing the imaging contrast and enhancing the imaging resolution.The trilayer resist may also include a photoresist layer formed on topof the middle layer. The photoresist layer may include a photosensitivechemical and a polymeric material. In some embodiments, thephotosensitive layer utilizes a chemical amplification (CA) resistmaterial. For example, a positive CA resist material includes a polymermaterial that turns soluble to a developer such as a base solution afterthe polymeric material is exposed and reacted with acid. Alternatively,the CA resist material can be negative and include a polymer materialthat turns insoluble to a developer such as a base solution after thepolymer is exposed and reacted with acid. The photoresist layer may alsoinclude one or more of a solvent, a photo-acid generator (PAG), and/or aquencher. Of course, it is understood that a trilayer resist is only oneof a wide range of exemplary materials represented by layer 402.

Before a film-forming material is dispensed on a layer 402, a primingmaterial may be applied to the layer 402. It has been determined throughinvestigation and experimentation that some difficulties inducing thefilm-forming liquid to cover the layer 402 arise from chemicalproperties of the layer 402 being coated. Specifically, it has beendetermined that these properties cause the priming material, thefilm-forming liquid, or both to resist dispersing uniformly. However, ithas also been determined that by selecting or otherwise configuring apriming material based on, in part, attributes of the substrate 102 andspecifically the material layer 402 being coated, coverage can beimproved far more than expected. As a result, the occurrence of dryspots, ridges, irregularities, and other imperfections may bedramatically reduced.

Accordingly, referring to block 304 of FIG. 3, a priming material isselected. The selected priming material is applied to the substrate 102before the film-forming liquid and may be selected to facilitate theflow of the film-forming liquid during the spin coating process. In thatregard, the priming material may be selected and/or otherwise configuredbased on, in part, attributes of the material layer 402 being coatedand/or attributes of the film forming liquid being applied to thepriming material.

One aspect of the material layer 402 that may be considered is the wateraffinity (e.g., hydrophobic or hydrophilic nature) of the material layer402. Thus, the priming material may be selected to have a similar wateraffinity to the material layer 402. In other words, a hydrophobicpriming material may be selected for coating a hydrophobic materiallayer 402 and vice-versa. The degree to which the material layer 402 ishydrophobic or hydrophilic may also be considered. For example, astrongly hydrophobic priming material may be selected for application ona strongly hydrophobic material layer 402. Additionally, or in thealternative, the water affinity of the film-forming liquid may also beconsidered, and the priming material may be selected to have a similarwater affinity to the film-forming liquid. In that way, a hydrophobicpriming material may be selected for use with a hydrophobic film-formingliquid and vice-versa. The degree to which the film-forming liquid ishydrophobic or hydrophilic may also be considered. In examples in whichthe material layer 402 and the film-forming liquid differ in wateraffinity or degree of affinity, the priming material may be configuredto have a first portion tuned to the water affinity of the materiallayer 402 and a second portion tuned to the water affinity of thefilm-forming liquid.

Another aspect of the material layer 402 and/or film-forming liquid thatmay be considered is the polarity (e.g., polar or non-polar nature). Thepolarity as well as the degree to which a compound is polar or non-polarmay both be considered. Accordingly, the priming material may beselected to have a similar polarity to the material layer 402 and/or thefilm-forming liquid. In that regard, a polar priming material may beselected for application on a polar material layer 402 and vice-versa,and a polar priming material may be selected for use with a polarfilm-forming liquid and vice versa. In examples in which the materiallayer 402 and the film-forming liquid differ polarity or degree ofpolarity, the priming material may be configured to have a first portiontuned to the polarity of the material layer 402 and a second portiontuned to the polarity of the film-forming liquid.

Examples of suitable priming materials are described with reference toFIGS. 5-7. Referring first to FIG. 5, a chemical structure of a primingmaterial molecule 500 is shown. Specifically, the illustrated moleculeis propylene glycol, and it represents a class of priming materials withtwo sets of adhesion groups, both of which have similar properties. Thepriming material molecule has a first adhesion group 502, which may betuned to one of the material layer 402 or the film-forming liquid, and asecond adhesion group 504, which may be tuned to the other of thematerial layer 402 or the film-forming liquid. In the example ofpropylene glycol and other suitable priming materials of this class,both adhesion groups 502 and 504 are polar and hydrophilic, making thisclass of priming material well-suited for use in applications where boththe material layer 402 and the film-forming liquid are polar and/orhydrophilic. Suitable chemical structures for adhesion groups 502 and504 include hydroxyl groups, amine groups, amide groups, thiol groups,esters, carboxylic acid, anhydride groups, silane, epoxy groups,ketones, cyano groups, isocyano groups, imide groups, and/or othersuitable groups. Another exemplary priming material in this class isdiethylene glycol.

The adhesion groups 502 and 504 may be joined by a linking chain 506 ofany suitable molecular length and composition such as a substituted orunsubstituted alkyl, a substituted or unsubstituted aryl, a substitutedor unsubstituted heteroaryl, a substituted or unsubstitutedheterocycloalkyl, and/or other suitable chain. The number of atoms inthe linking chain 506 may affect the evaporation rate of the primingmaterial. Many of the parameters used to apply the priming material(e.g., temperature, spin speed, spin time, etc.) depend on theevaporation rate, and accordingly, the composition of the linking chain506 may be selected to control the dispersal, thickness, and longevityof the priming material during the spin coating process.

Referring to FIG. 6, a chemical structure of a priming material molecule600, specifically diethyl ether, is shown and represents a class ofpriming materials with two sets of adhesion groups, both of which havesimilar properties. The priming material molecule has a first adhesiongroup 602, which may be tuned to one of the material layer 402 or thefilm-forming liquid, and a second adhesion group 604, which may be tunedto the other of the material layer 402 or the film-forming liquid. Incontrast to the examples of FIG. 5, diethyl ether and other suitablepriming materials in this class include adhesion groups 602 and 604 thatare non-polar and/or hydrophobic, making this class of priming materialwell-suited for use in applications where both the material layer 402and the film-forming liquid are non-polar and/or hydrophobic. Suitablechemical structures for adhesion groups 602 and 604 include alkylgroups, phenyl groups, biphenyl groups, benzyl groups, ether groups,cycloalkyl groups, aromatic rings, and/or other suitable groups.

As in the previous examples, the adhesion groups 602 and 604 may bejoined by a linking chain 606 of any suitable molecular length andcomposition such as a substituted or unsubstituted alkyl, a substitutedor unsubstituted aryl, a substituted or unsubstituted heteroaryl, asubstituted or unsubstituted heterocycloalkyl, and/or other suitablechain. The number of atoms in the linking chain 606 may be selected tocontrol the dispersal, thickness, and longevity of the priming materialduring the spin coating process.

Referring to FIG. 7, a chemical structure of a priming material molecule700, specifically 2-heptanone, is shown and represents priming materialswith two sets of adhesion groups that have different properties. Thepriming material molecule has a first adhesion group 702 that may betuned to one of the material layer 402 or the film-forming liquid and ispolar and/or hydrophilic. The molecule also includes a second adhesiongroup 704 that may be tuned to the other of the material layer 402 orthe film-forming liquid and is non-polar and/or hydrophobic. This classof priming material well-suited for use in applications where either thematerial layer 402 or the film-forming liquid is polar and/orhydrophilic while the other is non-polar and/or hydrophobic. Suitablechemical structures for the polar/hydrophilic adhesion group 702 includehydroxyl groups, amine groups, amide groups, thiol groups, esters,carboxylic acid, anhydride groups, silane, epoxy groups, ketones, cyanogroups, isocyano groups, imide groups, and/or other suitable groups.Suitable chemical structures for the non-polar/hydrophobic adhesiongroup 704 include alkyl groups, phenyl groups, biphenyl groups, benzylgroups, ether groups, cycloalkyl groups, aromatic rings, and/or othersuitable groups.

As in the previous examples, the adhesion groups 702 and 704 may bejoined by a linking chain 706 of any suitable molecular length andcomposition such as a substituted or unsubstituted alkyl, a substitutedor unsubstituted aryl, a substituted or unsubstituted heteroaryl, asubstituted or unsubstituted heterocycloalkyl, and/or other suitablechain. The number of atoms in the linking chain 706 may be selected tocontrol the dispersal, thickness, and longevity of the priming materialduring the spin coating process.

In addition to one or more of the molecules of FIGS. 5-7, the primingmaterial may include one or more surfactants, solvents, or otheradditives. One advantage associated with some of the above molecules isthat they may be used as a priming material without additionalsurfactants or solvents. This may eliminate an evaporation step betweenapplication of the priming material and the film-forming material.

Referring to block 306 of FIG. 3 and to FIG. 8, the selected primingmaterial 802 is dispensed on a central portion of the substrate 102 ontop of the layer 402 for which it is configured. In some embodiments, anozzle 108 is moved from a home position suitable for loading thesubstrate 102 to a position directly over the center of the substrate102, and the priming material 802 is dispensed on the substrate 102through the nozzle 108. The chuck 104 may begin rotating the substrate102 at any time before, during, and/or after the dispensing of thepriming material 802. In an exemplary embodiment, the substrate 102remains stationary during an initial portion of the dispensing until afirst portion of the priming material 802 has been dispensed, and thechuck 104 begins to rotate the substrate 102 after the first portion ofthe priming material 802 has been dispensed. In the example, the nozzle108 continues to dispense a remaining portion of the priming material802 while the substrate 102 spins. Centrifugal tendencies caused by therotation of the substrate 102 cause the priming material 802 to be drawnfrom the center to the perimeter of substrate 102.

Dispensing the priming material 802 may include applying heat and/orgasses to the substrate 102 to control dispersal and evaporation of thepriming material 802. For example, a nozzle 108 attached to the armature110 or the downdraft air flow device 112 may provide an inert gas suchas nitrogen, helium, or argon on the substrate surface to helpdistribute the priming material 802. Furthermore, at any time before,during, and/or after the dispensing of the priming material 802, aheating element 114 of the spin coating system 100 may apply heat to thesubstrate 102 to control primer viscosity, evaporation, and/or otheraspects of the spin coating process. These mechanisms and others areused to achieve good coverage of the substrate 102 without overly dryingthe priming material 802 before the film-forming liquid is applied.Particular attention may be paid to the coverage of the priming material802 at the substrate perimeter where the priming material 802 may bethinnest.

Referring to block 308 of FIG. 3 and to FIG. 9, the film-forming liquid902 is dispensed on the central portion of the substrate 102. Thefilm-forming liquid 902 may be dispensed by the same nozzle as thepriming material 802 or different nozzle 108 may be used. The chuck 104may rotate the substrate 102 at any time before, during, and/or afterthe dispensing of the film-forming liquid 902. In an exemplaryembodiment, the substrate 102 remains stationary until a first portionof the film-forming liquid 902 has been dispensed, and begins to rotatethe substrate 102 while the nozzle 108 continues to dispense a remainingportion of the film-forming liquid 902. The remaining portion may bedispensed while the substrate is rotated. The rotation of the substrate102 causes the film-forming liquid 902 to be driven from the center tothe perimeter of substrate 102.

Similar to the priming material 802, dispensing the film-forming liquid902 may include applying heat and/or gasses to the substrate 102 tocontrol dispersal and evaporation of the film-forming liquid 902. Forexample, a nozzle 108 or downdraft air flow device 112 may supply aninert gas such as nitrogen to distribute the film-forming liquid 902across the substrate 102. Likewise, at any time before, during, and/orafter the dispensing of the priming material, a heating element 114 ofthe spin coating system 100 may apply heat to the substrate 102 tocontrol the evaporation of the film-forming liquid 902. These mechanismsand others are used to achieve good coverage of the substrate 102particularly at the perimeter where the film-forming liquid 902 may bethinnest.

By using a priming material 802, the film-forming liquid 902 maydisperse across the surface of the substrate 102 more evenly.Specifically, a priming material 802 tuned based on the layer 402 beingcoated and/or the film-forming liquid 902 provides a better interfacebetween the substrate 102 and the film-forming liquid 902 to facilitateeven dispersal. As a result, the material remaining after thefilm-forming liquid 902 dries may have a more consistent thickness withfew or no dry spots where the substrate 102 lacks any film material.Moreover, the use of such a priming material 802 may greatly reduce theamount of film-forming liquid 902 used to coat the substrate. In oneexemplary test, one cubic centimeter (1 cm³) of a photoresistfilm-forming liquid 902 applied over a priming material 802 as describedherein was used to cover a substrate 102 to a desired thickness withoutdry spots. In contrast, more than five cubic centimeters (5 cm³) of thesame film-forming liquid 902 was needed to produce the same degree ofcoverage without the priming material. Because the priming material 802is cheap by comparison, the cost saving per substrate 102 may besubstantial. Of course, these advantages are merely exemplary, and noadvantage is characteristic of or required for any particularembodiment.

Referring to block 310 of FIG. 3 and to FIG. 10, the film-forming liquid902 is solidified by evaporating a solvent within the film-formingliquid 902 and evaporating any remaining portion of the priming material802. Solidification leaves behind a component of the film-forming liquid902 as a material film 1002 (e.g., a photoresist film, an antireflectivecoating film, a hard mask film, etc.) of a desired thickness.Evaporation and solidification may occur during the dispersal andspinning processes and block 308 and may continue during a post-spinphase. During the post-spin phase, heat and/or gasses may be applied tothe substrate 102 to control evaporation. For example, a gas deliverynozzle 108 or a downdraft air flow device 112 may provide ambient airand/or an inert gas such as nitrogen, helium, or argon on the substratesurface. The supplied gas may be heated to a designated temperature,which may vary throughout the process. Similarly, a heating element 114of the spin coating system 100 may apply heat to the substrate 102 tocontrol substrate temperature.

Referring to block 312 of FIG. 3 and to FIG. 11, an edge bead removalprocess may be performed on the film 1002. While the film 1002 tends tobe thinner towards the perimeter of the substrate 102, at the extremeedge, surface tension and viscosity of the film-forming liquid 902 maycreate a bulge or bead 1102 at the edge of the substrate 102. The edgebead may be removed by applying a solvent or an acid to the film 1002while the substrate 102 is spun. Additionally on in the alternative, aphotosensitive film 1002 may undergo an optical bead removal where thebead 1102 is exposed to lithographic energy. Because it has beenexposed, the bead 1102 will be removed when the photosensitive film 1002is developed.

Referring to block 314 of FIG. 3, the substrate 102 containing the film1002 is provided for further fabrication. In the case of a photoresistfilm 1002, further fabrication may include a lithographic exposure. Anexemplary photolithographic patterning process includes soft baking ofthe photoresist film 1002, mask aligning, exposure, post-exposurebaking, developing the film 1002, rinsing, and drying (e.g., hardbaking). In the case of an anti-reflective coating film 1002 or a hardmask film 1002, further fabrication may include any suitable etchingprocess, deposition process, implantation process, epitaxy process,and/or any other fabrication process to be performed on the film 1002.In various examples, the film 1002 is used to fabricate a gate stack, tofabricate an interconnect structure, to form non-planar devices byetching to expose a fin or by epitaxially growing fin material, and/orother suitable applications. For example, in that regard, the substrate102 and the film 1002 may be used to fabricate an integrated circuitchip, a system on a chip (SOC), and/or a portion thereof, and thus thesubsequent fabrication processes may form various passive and activemicroelectronic devices such as resistors, capacitors, inductors,diodes, metal-oxide semiconductor field effect transistors (MOSFET),complementary metal-oxide semiconductor (CMOS) transistors, bipolarjunction transistors (BJT), laterally diffused MOS (LDMOS) transistors,high power MOS transistors, other types of transistors, and/or othercircuit elements.

Thus, the present disclosure provides a spin coating technique and apriming material for forming thin films that offers superior coveragewith reduced fluid utilization. In some embodiments, the provided methodincludes receiving a substrate and identifying a material of thesubstrate upon which a layer is to be formed. A priming material isdispensed on the material of the substrate, and a film-forming materialis applied to the priming material. The priming material includes amolecule containing a first group based on an attribute of the materialand a second group based on an attribute of the film-forming material.In some such embodiments, the first group is configured to have a wateraffinity that corresponds to a water affinity of the material, and thesecond group is configured to have a water affinity that corresponds toa water affinity of the film-forming material. In some such embodiments,the first group is configured to have a degree of polarity thatcorresponds to a degree of polarity of the material, and the secondgroup is configured to have a degree of polarity that corresponds to adegree of polarity of the film-forming material. In some suchembodiments, the molecule of the priming material further includes alinking structure joining the first group and the second group, wherethe linking structure includes at least one of: an alkyl structure, anaryl structure, a heteroaryl structure, or a heterocyclo alkylstructure.

In further embodiments, the provided method includes receiving asubstrate having a material at a top surface of the substrate andselecting a priming material for application using a spin coatingtechnique based on a property of the material of the substrate. Theselected priming material is applied to the material of the substrate bya process that includes rotating the substrate to disperse the primingmaterial radially on the substrate. A film-forming material is appliedto the priming material by a process that includes rotating thesubstrate to disperse the film-forming material radially on thesubstrate. The priming material and the film-forming material areevaporated to leave a component of the film-forming material in a solidform. In some such embodiments, the priming material includes amolecular group configured based on a polarity of the material. In somesuch embodiments, the priming material includes a molecular groupconfigured based on a water affinity of the material. In some suchembodiments, the priming material is selected further based on aproperty of the film-forming material and has a first molecular groupbased on the property of the material of the substrate and a secondmolecular group based on the property of the film-forming material.

In yet further embodiments, a spin coating primer is provided thatincludes a molecule having a first molecular group associated with asubstrate material and a second molecular group associated with afilm-forming material to be applied on the spin coating primer. In somesuch embodiments, one of the first and second molecular groups includesat least one of: a hydroxyl group, an amine group, an amide group, athiol group, an ester, carboxylic acid, an anhydride group, silane, anepoxy group, a ketone, a cyano group, an isocyano group, or an imidegroup. In some such embodiments, one of the first and second moleculargroups includes at least one of: an alkyl group, a phenyl group, abiphenyl group, a benzyl group, an ether group, a cycloalkyl group, oran aromatic ring. The molecule may further include a linking structurelinking the first molecular group and the second molecular group such asan alkyl structure, an aryl structure, a heteroaryl structure, or aheterocycloalkyl structure.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of circuit device fabrication, themethod comprising: receiving a semiconductor substrate on a chuck, thesemiconductor substrate comprising a first surface directed away fromthe chuck and a second surface opposite the first surface and contactingthe chuck; identifying a material of the semiconductor substrate uponwhich a layer is to be formed; prior to dispensing a liquid primingmaterial on the first surface of the semiconductor substrate, heatingthe semiconductor substrate from the second surface of the semiconductorsubstrate using one or more heating elements disposed below the chuck;dispensing, with a liquid supply nozzle, the liquid priming material ona central portion of the first surface of the semiconductor substratewhile continuing to heat the semiconductor substrate from the secondsurface of the semiconductor substrate using the one or more heatingelements, such that during a phase of the dispensing, the centralportion of the first surface of the semiconductor substrate is coveredby the liquid priming material, while a continuous annular regionremains free of the liquid priming material; prior to drying the liquidpriming material, applying a film-forming material to the liquid primingmaterial on the central portion of the first surface of thesemiconductor substrate; rotating the semiconductor substrate todisperse the film-forming material from the central portion of the firstsurface of the semiconductor substrate to a peripheral portion of thefirst surface of the semiconductor substrate, wherein the liquid primingmaterial facilitates dispersal of the film-forming material from thecentral portion of the first surface of the semiconductor substrate tothe peripheral portion of the first surface of the semiconductorsubstrate based on containing a first group based on an attribute of thematerial of the semiconductor substrate and a second group based on anattribute of the film-forming material; and evaporating the liquidpriming material and the film-forming material to leave a component ofthe film-forming material that physically contacts the first surface ofthe semiconductor substrate.
 2. The method of claim 1, wherein: a firstone of the first group and the second group includes at least one of: athiol group, an ester, an epoxy group, a ketone, a cyano group, or anisocyano group; and a second one of the first group and the second groupincludes at least one of: a benzyl group.
 3. The method of claim 1,wherein during the dispensing, the liquid priming material descends fromthe liquid supply nozzle to the material of the semiconductor substratein a substantially vertical path.
 4. The method of claim 1, wherein anaxis of the liquid supply nozzle is substantially perpendicular to thefirst surface of the semiconductor substrate.
 5. The method of claim 1,further comprising selecting the liquid priming material based on anaffinity of the liquid priming material to the material of thesemiconductor substrate and an affinity of the liquid priming materialto the film-forming material, wherein the affinity of the liquid primingmaterial to the material of the semiconductor substrate is differentthan the affinity of the film-forming material to the material of thesemiconductor substrate.
 6. The method of claim 1, further comprisingselecting the liquid priming material based on an affinity of the liquidpriming material to the material of the semiconductor substrate and theaffinity of the liquid priming material to the film-forming material,wherein the liquid priming material has the same affinity, but to adifferent degree, to the material of the semiconductor substrate as thefilm-forming material.
 7. The method of claim 6, wherein the selectingof the liquid priming material is further based on a degree of theaffinity of the liquid priming material to the material of thesemiconductor substrate and the degree of the affinity of the liquidpriming material to the film-forming material.
 8. The method of claim 1,wherein in the dispensing of the liquid priming material, the liquidpriming material is dispensed on the central portion of the firstsurface of the semiconductor substrate before a gas is blown onto thedispensed liquid priming material.
 9. The method of claim 1, furthercomprising introducing a gas to reduce a rate of the evaporating.
 10. Amethod of film formation, the method comprising: receiving a substratehaving a material at a top surface of the substrate; selecting a liquidpriming material, the liquid priming material facilitating dispersal ofa film-forming material from a central portion of the substrate to aperipheral portion of the substrate, the liquid priming materialincluding a chemical with a first group based on a property of thematerial at the top surface of the substrate and a second group based ona property of a film-forming material to be applied on the liquidpriming material; prior to dispensing the selected liquid primingmaterial on the top surface of the substrate, heating the substrate froma bottom surface of the substrate using a heating element disposed belowbottom surface of the substrate; dispensing the selected liquid primingmaterial on the top surface of the substrate while continuing to heatthe substrate from the bottom surface of the substrate using the heatingelement disposed below bottom surface of the substrate; spin coating theliquid priming material onto the substrate while continuing to heat thesubstrate from the bottom surface of the substrate using the heatingelement disposed below bottom surface of the substrate, wherein during aphase of the spin coating of the liquid priming material, the centralportion of the substrate onto which the liquid priming material isapplied is covered by the liquid priming material, while a continuousannular region remains free of the liquid priming material, and whereinthe spin coating of the liquid priming material includes rotating thesubstrate to radially disperse the liquid priming material on thesubstrate and applying heat to the top surface of the substrate withoutdrying the liquid priming material prior to applying the film-formingmaterial; applying the film-forming material to the liquid primingmaterial by spin coating the film-forming material onto the liquidpriming material while continuing to heat the substrate from the bottomsurface of the substrate using the heating element disposed below bottomsurface of the substrate, wherein during a phase of the spin coating ofthe film-forming material, the central portion of the substrate ontowhich the film-forming material is applied is covered by thefilm-forming material, while a continuous annular region remains free ofthe film-forming material, and wherein the spin coating of thefilm-forming material includes rotating the substrate to radiallydisperse the film-forming material on the liquid priming material; andevaporating the liquid priming material and the film-forming material toleave a component of the film-forming material that physically contactsthe substrate.
 11. The method of claim 10, wherein the chemical of theliquid priming material includes at least one of: a hydroxyl group, anamine group, an amide group, a thiol group, an ester, carboxylic acid,an anhydride group, silane, an epoxy group, a ketone, a cyano group, anisocyano group, or an imide group based on the property of the materialat the top surface of the substrate.
 12. The method of claim 10, whereinthe chemical of the liquid priming material includes at least one of: analkyl group, a phenyl group, a biphenyl group, a benzyl group, an ethergroup, a cycloalkyl group, or an aromatic ring based on the property ofthe material at the top surface of the substrate.
 13. The method ofclaim 10, wherein the continuous annular region remains free of theliquid priming material until the spin coating radially disperses theliquid priming material from the central portion of the substrate to thecontinuous annular region.
 14. The method of claim 10, furthercomprising introducing a gas to reduce a rate of the evaporating.
 15. Amethod of circuit device fabrication, the method comprising: receiving asubstrate; identifying a semiconductor substrate material upon which alayer is to be formed; prior to dispensing a liquid priming material onthe semiconductor substrate material, applying heat to an underside ofthe substrate using a plurality of heating elements disposed below achuck supporting the substrate and contacting the underside of thesubstrate; dispensing, with a liquid supply nozzle, the liquid primingmaterial on a central portion of the semiconductor substrate materialwhile heating of the underside of the substrate using the plurality ofheating elements continues, wherein during a phase of the dispensing,the central portion of the substrate onto which the liquid primingmaterial is dispensed is covered by the liquid priming material, while acontinuous annular region remains free of the liquid priming material,wherein the liquid priming material facilitates dispersal of afilm-forming material from a central portion of the substrate to aperipheral portion of the substrate, the liquid priming materialincluding 2-heptanone, which has a first component with a first wateraffinity similar to that of the semiconductor substrate material and hasa second component with a second water affinity similar to that of afilm-forming material to be applied on the liquid priming material; andapplying the film-forming material to the liquid priming material on thecentral portion of the semiconductor substrate material while heating ofthe underside of the substrate using the plurality of heating elementscontinues, wherein during a phase of the applying, the central portionof the substrate onto which the film-forming material is applied iscovered by the film-forming material, while a continuous annular regionremains free of the film-forming material, and wherein the applyingincludes rotating the substrate to disperse the film-forming materialfrom the central portion of the substrate to the continuous annularregion of the substrate.
 16. The method of claim 15, wherein the liquidpriming material further includes a molecule having a further firstcomponent and a further second component, wherein the further firstcomponent includes at least one of: a hydroxyl group, an amine group, anamide group, a thiol group, an ester, carboxylic acid, an anhydridegroup, silane, an epoxy group, a ketone, a cyano group, an isocyanogroup, or an imide group.
 17. The method of claim 16, wherein thefurther second component includes at least one of: an alkyl group, aphenyl group, a biphenyl group, a benzyl group, an ether group, acycloalkyl group, or an aromatic ring.
 18. The method of claim 15,wherein the dispensing of the liquid priming material includes rotatingthe substrate to distribute the liquid priming material on thesemiconductor substrate material.
 19. The method of claim 15, furthercomprising evaporating the liquid priming material and the film-formingmaterial to leave a component of the film-forming material thatphysically contacts a topside of the semiconductor substrate material,and introducing a gas to reduce a rate of the evaporating.